The Iraqis' fierce resistance to foreigners (us) invading their country was predictable on any number of grounds. But perhaps the most interesting is the most fundamental: the theory of "ethnic nepotism." This explains the tendency of humans to favor members of their own racial group by postulating that all animals evolve toward being more altruistic toward kin in order to propagate more copies of their common genes.

Which doesn't mean that kin groups always cooperate—they also compete among themselves, in a sort of sibling rivalry writ large. But nepotistic solidarity still matters.

Even the notoriously fractious Afghan Pashtuns think in terms of: "I against my brother. My brother and I against my cousin. My cousin and we against the world." (Note that, by maintaining a smaller footprint in Afghanistan and letting the Afghans go back to being Afghans, we've provoked much less nationalist backlash there.)

You may not have ever heard of ethnic nepotism before. That's largely because the most media savvy-explicators of Darwinism—such as Richard Dawkins, recently voted Britain's top public intellectual by Prospect magazine—are terrified that their entire field might be tarred as "racist" if the concept is given a fair public discussion.

There are no clear boundaries between extended family, tribe, ethnic group, or race. So van den Berghe coined the term "ethnic nepotism" to describe the human tendency to favor"our people."

Ethnocentrism, clannishness, xenophobia, nationalism, and racism are the almost inevitable flip sides of ethnic nepotism. (I say almost because it's important to note that you can be patriotic and work for the good of your own fellow citizens without overtly wishing ill toward any other country. Nonetheless, even patriotism still implies discrimination against noncitizens.)

Hamilton, the leading evolutionary theorist of the second half of the 20th Century, had figured out the mathematics and extraordinary implications of an explanation for nepotism that had been kicking around half-formed among biologists.

Hamilton pointed out that it was often useful to think of "survival of the fittest" from the point of view, as it were, of individual genes. A gene that encourages you to sacrifice your life to save two brothers or eight cousins would tend to spread.

Hamilton used his new perspective to explain a mystery that had perplexed Darwin a century before: the extreme degree of nepotistic self-sacrifice among social insects. Worker ants give up reproducing in order to help their sister, the queen, reproduce on a vast scale. Hamilton pointed out that while most species' siblings share 50 percent of their genes, ant sisters share 75 percent. This makes self-sacrifice by workers more genetically profitable.

This gene-centric viewpoint was made understandable to the reading public by Edward O. Wilson's 1975 book Sociobiology and Richard Dawkins' celebrated 1976 book, The Selfish Gene . (A better title for Dawkins' book would have been The Dynastic Gene, since your genes spread by helping promulgate copies of themselves in one's relatives).

E.O. Wilson's description in his delightful autobiography Naturalist of how he wrestled with Hamilton's epochal papers during an 18-hour train ride in 1965 is a classic:

"Impossible, I thought, this can't be right. Too simple… By dinnertime, as the train rumbled on into Virginia, I was growing frustrated and angry… And because I modestly thought of myself as the world authority on social insects, I also thought it unlikely that anyone else could explain their origin, certainly not in one clean stroke… By the time we reached Miami, in the early afternoon, I gave up. I was a convert and put myself in Hamilton's hands. I had undergone what historians of science call a paradigm shift."

"... I hope to produce evidence that some things which are often treated as purely cultural in humans—say racial discrimination—have deep roots in our animal past and thus are quite likely to rest on direct genetic foundations."

Richard Dawkins' tremendous career as a science journalist has been built on his talent at translating Hamilton's formulas into engaging prose. But he has long denied the possibility of ethnic nepotism, even though Hamilton had published an elaborate model of it the year before Dawkins published The Selfish Gene.

Dawkins' political correctness was all too apparent the 1995 interview with him conducted by Frank Miele for The Skeptic magazine:

Miele: Shortly after publication of The Selfish Gene, you wrote a letter to the editor of Nature … in which you stated that kin selection theory in no way provides a basis for understanding ethnocentrism. You said you made this statement, in part at least, to counter charges that were being made in the UK at that time by Marxist critics that Selfish Gene Theory was being used by the British National Front to support their Fascist ideology. In retrospect, do you think you went too far in trying to distance yourself from some would-be and very unwanted enthusiasts, or not far enough?

Dawkins: As to distancing myself from the National Front, that I did! The National Front was saying something like this, "kin selection provides the basis for favoring your own race as distinct from other races, as a kind of generalization of favoring your own close family as opposed to other individuals." Kin selection doesn't do that! Kin selection favors nepotism towards your own immediate close family. It does not favor a generalization of nepotism towards millions of other people who happen to be the same color as you. Even if it did, and this is a stronger point, I would oppose any suggestion from any group such as the National Front, that whatever occurs in natural selection is therefore morally good or desirable. We come back to this point over and over again. I'm definitely not one who thinks that "is" is the same as "ought."

The purpose of science, however, is not to proclaim better morals or to distance oneself from the politically unpalatable, but to help us make better predictions.

And in fact Miele easily forced Dawkins to admit that his strident pronouncement against the feasibility of ethnic nepotism was dubious:

Miele: Could there be selection for a mechanism that would operate like this--"those who look like me, talk like me, act like me, are probably genetically close to me. Therefore, be nice, good, and altruistic to them. If not avoid them?" And could that mechanism later be programmed to say, "Be good to someone who wears the same baseball cap, the same Rugby colors, or whatever?" That is, could evolution have a produced a hardware mechanism that is software programmable?

Dawkins: I think that's possible.

Hamilton could have been describing Dawkins' political weaseling when he recounted in 1996 the reception his 1975 paper on ethnic nepotism had received in a review by

"noted anthropologist, S.L. Washburn, in which, singling my paper out of the whole volume, he called it 'reductionist, racist, and ridiculous.' ... I wonder if people who struggle to extend the frontiers of a discipline against a current of peer disapproval sometimes need to convince themselves and other that they are not quite the heretics and outlaws everyone thinks and this need is expressed through an extra militancy against further extension in the direction they themselves have been taking… It is a pity to see scientists struggling to tie each other's hands in respect of some kinds of understanding and in effect crippling themselves …"

The main objection that Dawkins raises to ethnic nepotism is that Hamiltonian kin selection only applies to close kin, presumably because genetic similarity diffuses so rapidly as you move outward in your family tree.

To use Hamilton's way of calculating, you are 1/2 related to your brother, 1/8 to your first cousin, 1/32 to your second cousin, 1/128 to your third cousin, etc.

Thus genetic anthropologist Henry Harpending long pooh-poohed ethnic nepotism until he finally sat down to do the math. Then, Harpending discovered that the effect was twice as strong as had been suggested. (This discovery is recounted in Frank Salter's important new bookOn Genetic Interests: Family, Ethny, and Humanity in an Age of Mass Migration).

Take race denier Richard Lewontin's famous 1972 finding that only 15% of genetic variation is among population groups. This is always interpreted in the popular press to mean that, because there is more genetic diversity within racial groups than between them, therefore (non sequitur alert!) RACIAL DIFFERENCES DO NOT EXIST!!!...

Harpending says the variation between groups is even lower, more like 12.5%, so let's use that.

What Harpending discovered, and anthropologist Vincent Sarich confirmed, is that Lewontin was using Sewall Wright's way of calculating relatedness, and you need to about double it to make it equivalent to Hamilton's way. So, 12.5% times two is 25%, which is the degree of relatedness between an uncle and his nephew…which, after all, is where the word "nepotism" comes from!

In other words, on average, people are as closely related to other members of their subracial "ethnic" group (e.g., Japanese or Italian) versus the rest of the world as they are related to their nephew versus the rest of their ethnic group.

(Sarich and Miele have explained the genetics of Harpending's discovery using slightly more aggressive assumptions than I did above).